Absence of additional improvement in outcome of patients receiving cardiac resynchronization therapy paced at the most delayed left ventricular region

Three-dimensional echocardiography to assess left ventricular geometry and function

Introduction: Quantification of left ventricular (LV) size and function represents the most frequent indication for an echocardiographic study. New echocardiographic techniques have been developed over the last decades in an attempt to provide a more comprehensive, accurate, and reproducible assessment of LV function.Areas covered: Although two-dimensional echocardiography (2DE) is the recommended imaging modality to evaluate the LV, three-dimensional echocardiography (3DE) has proven to be more accurate, by avoiding geometric assumptions about LV geometry, and to have incremental value for outcome prediction in comparison to conventional 2DE. LV shape (sphericity) and mass are actually measured with 3DE. Myocardial deformation analysis using 3DE can early detect subclinical LV dysfunction, before any detectable change in LV ejection fraction.Expert opinion: 3DE eliminates the errors associated with foreshortening and geometric assumptions inherent to 2DE and 3DE measurements approach very closely those obtained by CMR (the current reference modality), while maintaining the unique clinical advantage of a safe, highly cost/effective, portable imaging technique, available to the cardiologist at bedside to translate immediately the echocardiography findings into the clinical decision-making process.

Using three-dimensional echocardiography to guide left ventricle lead position in cardiac resynchronization therapy: does it make any difference

BACKGROUND

Cardiac resynchronization therapy (CRT) is an effective treatment for patients with advanced heart failure. Nearly 30% of candidates are inadequate responders. Proper patient selection, left ventricle (LV) lead placement optimization, and optimization of the programming of the CRT device are important approaches to improve outcome of CRT. We examined the role of three-dimensional (3D) echocardiography in determining the optimal LV lead position as a method of optimizing CRT response.

METHODS

Forty-seven patients with a mean age of 60.2 ± 11.1 years including five (10.6%) females, all having advanced CHF (EF <35%, LBBB >120 mesc, or non-LBBB >150 msec, with NYHA II-III or ambulatory class IV) were enrolled. Detailed history (NYHA class, Minnesota living with heart failure questionnaire), clinical examination, 6-min walk test, and standard 2D echocardiography were done in all cases. 3D echo detailed analysis of the LV 16 segments was done to determine the latest wall to reach the minimal systolic volume. Multisite pacing was done blind to the 3D echo data achieving a stable LV lead position in mid LV segment. This exact fluoroscopic site was determined (in two orthogonal views) and correlated with 3D most delayed area using a resized 16-segment schema. Patients were classified retrospectively into group A with concordance between the delayed LV area and LV lead position and group B with discordance between both. Patients were followed up after 3-6 (5.1 ± 1.8) months. Patients with reduction of 2D LV end-systolic volume of ≥10% at follow-up were termed volumetric responders. Poorly echogenic patients and those with decompensated NYHA class IV, sustained atrial arrhythmias, and rheumatic or congenital heart diseases were excluded.

RESULTS

LV lead placement was concordant in 22 (46.8%) cases. After the follow-up period, 31 (65.9%) of the study population were considered volumetric responders with no significant difference among both groups (14 (63.3%) in group A vs 17 (68%) in group B, p > 0.05). CRT insertion resulted in significant improvement of NYHA class in 36 (76.5%) cases, 6-min walk test (447.2 ± 127.0 vs 369.6 ± 87.5 m, p < 0.01), MLHFQ (58.1 ± 19.7 vs 69.6 ± 13.5, p < 0.01), QRS duration (131.2 ± 13.8 vs 149.4 ± 16 msec, p < 0.01), 2D LV EF 33.0 ± 9.5 vs 25.3 ± 6.5, p < 0.001), LVESV (156.0 ± 82.9 vs177.6 ± 92.7 ml, p < 0.05), and 3D LVEF (29.1 ± 9.0 vs 23.6 ± 5.9, p < 0.001) irrespective of the etiology of heart failure. However, there were no significant differences between both groups regarding the same parameters (6-min walk test 470.8 ± 128.7 vs 428.3 ± 126.8 m, MLHFQ 56.8 ± 20.0 vs 58.11 ± 19.0, QRS duration 129.9 ± 12.4 vs 132.1 ± 15.1 msec, 2D LVEF 30.9 ± 8.3 vs 34.58 ± 10.9, LVESV 173.0 ± 110.0 vs 143.0 ± 67.9, 3D LVEF 26 ± 8 vs 31 ± 9, for groups A and B, respectively, p < 0.05).

CONCLUSIONS

Standard anatomical LV lead placement remains a simple, practical, and effective method in patients undergoing CRT. 3D echocardiography-guided LV lead placement added no clinical benefit compared to standard techniques.

The clinical benefits of adding a third dimension to assess the left ventricle with echocardiography

Three-dimensional echocardiography is a novel imaging technique based on acquisition and display of volumetric data sets in the beating heart. This permits a comprehensive evaluation of left ventricular (LV) anatomy and function from a single acquisition and expands the diagnostic possibilities of noninvasive cardiology. It provides the possibility of quantitating geometry and function of LV without preestablished assumptions regarding cardiac chamber shape and allows an echocardiographic assessment of the LV that is less operator-dependent and therefore more reproducible. Further developments and improvements for widespread routine applications include higher spatial and temporal resolution to improve image quality, faster acquisition, processing and reconstruction, and fully automated quantitative analysis. At present, three-dimensional echocardiography complements routine 2DE in clinical practice, overcoming some of its limitations and offering additional valuable information that has led to recommending its use for routine assessment of the LV of patients in whom information about LV size and function is critical for their clinical management.

Three-dimensional echocardiography for left ventricular quantification: fundamental validation and clinical applications

One of the earliest applications of clinical echocardiography is evaluation of left ventricular (LV) function and size. Accurate, reproducible and quantitative evaluation of LV function and size is vital for diagnosis, treatment and prediction of prognosis of heart disease. Early three-dimensional (3D) echocardiographic techniques showed better reproducibility than two-dimensional (2D) echocardiography and narrower limits of agreement for assessment of LV function and size in comparison to reference methods, mostly cardiac magnetic resonance (CMR) imaging, but acquisition methods were cumbersome and a lack of user-friendly analysis software initially precluded widespread use. Through the advent of matrix transducers enabling real-time three-dimensional echocardiography (3DE) and improvements in analysis software featuring semi-automated volumetric analysis, 3D echocardiography evolved into a simple and fast imaging modality for everyday clinical use. 3DE provides the possibility to evaluate the entire LV in three spatial dimensions during the complete cardiac cycle, offering a more accurate and complete quantitative evaluation the LV. Improved efficiency in acquisition and analysis may provide clinicians with important diagnostic information within minutes. The current article reviews the methodology and application of 3DE for quantitative evaluation of the LV, provides the scientific evidence for its current clinical use, and discusses its current limitations and potential future directions.